Carboxyl-terminated polypropylene glycol (CTPPG) and epoxy-terminated polypropylene glycol(ETPPG) were synthesized from polypropylene glycol(PPG),the differential scanning calorimetry,dynamic mechanical thermal analysis,impact strength and impact fracture surface of the three different end group polypropylene glycol modified epoxy resin were investigated.The results showed that with the increase of reactivity between the end group of polypropylene glycol and epoxy resin,the cured epoxy resin tends to form homogeneous structure,and the Tg depressed.Both of PPG and ETPPG can obviously increase the impact strength.Test results showed that polypropylene glycol toughening epoxy resin is by the way of plasticization,and epoxy-terminated polypropylene glycol toughening epoxy resin is by the way of increasing the flexibility of the crosslinked network.
